Polish president's pilots 'knew plane was doomed'

Investigators blamed pilot error on Thursday for a crash that killed Poland's president, as harrowing details emerged of how the crew knew they were doomed after hitting trees while trying to land in Russia.

As Poland's national unity fractured over plans to bury president Lech Kaczynski in a castle alongside kings and heroes, officials in Warsaw and Moscow released the first results from analysis of the plane's black box flight recorders.

"The crew was aware of the inevitability of the coming catastrophe, if only due to the plane shaking after the wings hit the trees -- which we are certain happened," Poland's chief prosecutor Andrzej Seremet told commercial radio.

Colonel Zbigniew Rzepa, a Polish military prosecutor, said the pilots were aware of the imminent crash as the last seconds of the voice recordings "were dramatic", but did not elaborate.

The Polish presidential Tupolev Tu-154 crashed in thick fog Saturday near the western Russian city of Smolensk while taking a delegation to a memorial service for a World War II massacre.

All 96 people on board were killed.

Poland remains deep in mourning after its worst peacetime catastrophe and world leaders including US President Barack Obama plus royals from around the world are set to attend Kaczynski's state funeral on Sunday.

But protests have erupted over the choice of Krakow's historic Wawel castle, the resting place of Poland's past kings, a saint and national heroes, for the burial of the president and his wife Maria.

Hundreds of people rallied in Warsaw, Krakow, the Baltic port of Gdansk and Poznan in the west on Wednesday, while more than 42,000 people have signed up to a Facebook campaign against the decision.

Questions have also mounted over the cause of the crash.

Russian investigators said Thursday that initial findings from the jet's data and voice recorders said the crew may not have been aware of the particularities of the plane when they repeatedly tried to land.

"An analysis of the evidence, including the first results from the decoding of the black boxes, shows that an error in piloting led to the disaster," the Interfax news agency quoted a source close to the investigation as saying.

The official said it appeared that on its final attempt, the plane tried to land by levelling out its oblique descent approach to a horizontal angle in a bid to compensate for the bad weather.

But the source said a "particularity of the plane is that if its speed of descent is more that six metres per second, when the plane equalized and goes into a horizontal flight it loses altitude," the source said.